The head of the national crime agency has said UK's drugs strategy is "making no difference" and needs a radical new approach.

Sir Stephen Lander, the chairman of the Serious and Organised Crime Agency (Soca) - described as Britain's answer to the FBI - admitted that when it comes to the fight against drugs "we are not winning so we must try something else as well".

The former head of MI5 said that the traditional law enforcement approach to drugs - seizure and imprisonment - has failed to reduce the availability of illegal substances, such as cocaine and heroin, in this country.

Speaking on the first anniversary of the agency, which has a ?450m budget, he said: "The criminal law as the only means of defence [against drugs] is a flawed approach. It must be - we are not winning so we must try something else. Our analysis is that the criminal law is a necessary part of the tool kit, but not a sufficient one. We have to be ambitious about making a difference."

With a staff of 4,400, Soca took over the briefs of the National Crime Squad, the National Criminal Intelligence Service, the role of Customs in drug investigations and some functions of the Immigration Service.